Comparison of the membrane glycoproteins of control and malignant cells has revealed a difference in the carbohydrates bound to membrane proteins. The difference is growth associated and occurs in every membrane system of the cell. It is found in a wide variety of tumors both in culture and in vivo. Recent work reveals that the carbohydrates of most membrane glycoproteins are altered in a quantitative and qualitative manner. Our present methodology will permit us to isolate individual glycoproteins from control hamster and rat liver cells and these cells transformed by Rous virus or chemicals. Isolation and purification is achieved by SDS-PAGE and isoelectric focusing. Glycopeptides can now be separated into at least fifteen fractions by chromatography on columns of Sephadex G50, Con A-sepharose and DEAE-sephadex. The number, type and location of carbohydrate groups on a polypeptide chain as well as the composition and some structural features of individual glycopeptides will be determined. We also plan to study the biosynthesis of these structures and to investigate the effects of various glycopeptides and glycoproteins on cellular functions that are altered in ways believed to be characteristic of malignancy. Can the alteration in carbohydrates covalently bound to proteins be correlated with altered functions and behavior (adhesiveness, growth in soft agar, agglutinability, transport)?